Implementation status: to be implemented

Synopsis

#include <math.h>

double atanh(double x);
float atanhf(float x);
long double atanhl(long double x);

Description

The functions compute the inverse hyperbolic tangent of their argument x.

Arguments
x - the argument of atanh

Return value

Upon successful completion, these functions shall return the inverse hyperbolic tangent of their argument.

Errors

[EDOM](Domain Error) - The x argument is finite and not in the range [-1,1] or is ±Inf.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception is raised.

[ERANGE](Pole Error) - The x argument is ±1.
If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the divide-by-zero floating-point exception is raised.

[ERANGE](Range Error) - The value of x is subnormal.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno is set to [ERANGE]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow floating-point exception is raised.

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them is non-zero.